The following disclosure relates to electrical circuits and signal processing.
A transmitter (e.g., a transmitter in a data communication system) typically includes a driver chain, including multiple inverters (or buffers) that drive an input signal.
FIG. 1 shows a conventional driver chain 100 of a transmitter. Driver chain 100 includes a single voltage regulator 102 and an inverter chain 104. Voltage regulator 102 includes a bias current source 106 and a regulator 108. Inverter chain 104 includes (n) inverters 110(a)-110(n). Inverters 110(a)-110(n) can be progressively sized to optimize amplification of an input signal. Driver chain 100 can also include a decoupling capacitor 112. In general, voltage regulator 102 provides a stable bias (e.g., a bias voltage and/or bias current) to each of inverters 110(a)-110(n) and attenuates supply noise associated with a high-side supply voltage VDD through decoupling capacitor 112. A large capacitance value for decoupling capacitor 112 may cause a slow settling of high-side supply voltage VDD due to the memory effect of decoupling capacitor 112.
In a transmitter, one parameter that is generally controlled to within specified limits is jitter. Jitter represents a time difference between an ideal and an actual occurrence of an event. One type of jitter known as data-dependent jitter (or intersymbol interference (ISI)) is typically a result of bandwidth limitations of an associated driver chain (e.g., driver chain 100) in a given transmitter. Data-dependent jitter may be caused by a large, mutual coupling capacitance formed by multiple inverters of an inverter chain (e.g., inverter chain 104) being coupled through a shared inverter supply.